Heat radiator

ABSTRACT

1,001,934. Heat exchangers. WEBASTOWERK G.m.b.H. Aug. 4, 1964 [Nov. 1, 1963], No. 31074/64. Heading F4S. [Also in Division B3] A duct 2 having walls 1 of one metal, e.g. steel, has fins 3 of another metal, e.g. copper, soldered thereto in a non-reactive gas atmosphere, each fin or pair of fins being integral with a soldering strip 6 (Fig. 2, not shown) and having at least one dividing cut 7, 8 to relieve thermal stresses. Before soldering, the fins may be bound on to the duct by a wire loop 9 (Fig. 2, not shown) passing through the cuts.

R. FRIEDL ETAL HEAT RADIATOR Filed Sept. 50, 1964 Feb. 21, 1967 lnventors:

PE/NE/P F/P/EDL IPOBE/PTvm L/NDE My? K Attorney United States Patent3,305,013 HEAT RADIATOR Reiner Friedl, Starnberg, Upper Bavaria, andRobert von Linde, Grafelfing, Germany, assignors to Webasto WerkG.m.b.H., Munich, Germany Filed Sept. 30, 1964, Ser. No. 400,495 Claimspriority, application Switzerland, Nov. 1, 1963, 13,404/ 63 2 Claims.(Cl. 165-183) The invention relates to heat radiators of the kind inwhich the wall of a heating-gas duct consists of one metal e.g. alloyedor unalloyed steel, and on which fin elements or ribs of'another metal,e.g. copper (which may have a length of at least cm. and be soldered inposition in a protective gas furnace) are fastened to the duct by asoldering bridge which is preferably formed on each fin element, orbetween two adjacent fin elements.

The soldering of copper fin elements in a protective gas furnace on heatradiators of the aforesaid type has hitherto been difiicult, since whenthe soldered parts cooled the individual fin element usually becamepartly detached from the steel wall of the duct. It was' thereforenecessary to prevent this from happening by special means consisting ofvery firm fastening by means of wire, but even this was successful inonly a few cases, so that economical working in connection with thesoldering process has hitherto not been possible.

The present invention is based on the realization that the detachment ofthe fin elements is not only due to the different coefiicients ofexpansion of copper and steel, but also to the fact that the copper finelements cool substantially more quickly than the duct, particularly inthe parts of the fin elements remote from the soldered joint. In orderto avoid the consequent tensions inside the fin element, which lead tothe partial detachment at the soldered joints, it is therefore proposedaccording to the invention that each of the fin elements shall have atleast one dividing cut although still supported by the soldering bridge.The distance between a dividing cut or cuts and the nearest end of thefin element should be at most four times, but preferably less than threetimes, the height of the fin element.

According to one preferred embodiment of the invention, a dividing cutis in the form of a slot. In this case the slot may at the same time beused, by inserting a wire in the base of the slot, for fastening the finelement to the duct by means of this wire before the soldering operationis carried out.

If use is made of a cylindrical heating-gas duct, on which, viewed incross-section, radially mounted fin elements extending in the axialdirection of the duct are fastened, the dividing slots of the variousfin elements are, according to a further feature of the invention, ineach case disposed in a plane substantially at right-angles to the axisof the heating gas duct, so that with a wire which runs through all theslots lying in this plane it is possible to fasten all the fin elementson the wall of the heating gas duct in spaced peripheral positions.

, In the following description of one embodiment of a heat radiatoraccording to the invention reference is made to the accompanyingdrawings with the aid of which further features of the invention will beindicated. In the drawings FIGURE 1 shows a heat radiator according tothe invention, partly in section, and

FIGURE 2 shows the same in section along the lines IIII of FIGURE 1.

3,305,013 Patented Feb. 21, 1967 The wall 1 of a heating gas duct 2,which consists of alloyed or unalloyed steel, is provided with copperfin elements 3 which extend into a heating medium duct 5 formed by anouter casing 4. Each two adjacent buffer fin elements 3 are providedwith a soldering bridge 6 formed between them. As best seen in FIGURE 1,dividing slots 7 and 8 are provided in the fin elements 3 and lie ingroups in a plane substantially perpendicular to the axis of the heatinggas duct 2, preferably directly above the soldering bridges but, if aplurality of dividing slots are provided, particularly at the end of thefin element with reference to its height per unit of length, they mayalso end a certain distance above the soldering bridge.

The abovedescribed arrangement of the group of slots in a common planeaffords the advantage that before being soldered the fin elements can befastened to the duct by means of -a single wire 9 as shown for the sakeof greater clarity only in FIGURE 2. Corresponding wire fastenings, asnecessary, may be provided in the second or other groups of slots.

The invention is not restricted to the details of the embodimentdescribed above, but may be modified in various Ways without departingfrom the scope of the invention as defined in the appended claims.

'What we claim is:

1. A heat radiator having a cylindrical heating fluid duct of one metaland fin units of another metal having a different coefiicient ofexpansion and a second duct surrounding said units, said units havingfin elements projecting radially from said duct and being elongated inthe axial direction of said duct, said fin elements being formed inpairs each of which comprises a sheet of said other metal bentintermediate its width to form a central longitudinal loop and with oneof said fin elements at each side of said loop terminating in a freeedge, said fin units being soldered to said duct by means of continuoussoldering throughout the lengths of said loops, each of said finelements having a transverse slot in its radially outer portion, saidslots having their radially inner extremities terminating in relativelyclose proximity to said loops, and a binding wire around said units insaid slots.

2. A radiator according to claim 1 wherein each loop has a groove facingsaid first named duct and extending from end-to-end of the associatedunit to receive solder.

References Cited by the Examiner UNITED STATES PATENTS 851,978 4/1907Bigsby et al. -183 1,797,030 3/1931 Steenstrup 29'157.3 1,840,724 l/1932Koehring 29-493 X 2,737,370 3/1956 -Frisch et al. 165-180 X FOREIGNPATENTS 707,514 4/ 1931 France. 1,015,904 8/ 1952 France.

360,245 9/1921 Germany.

813,006 5/1959 Great Britain.

References Cited by the Applicant UNITED STATES PATENTS 2,298,249 10/1942 Brown.

ROBERT A. OLEARY, Primary Examiner.

N. R. WILSON, T. W. STREULE, Assistant Examiners.

1. A HEAT RADIATOR HAVING A CYLINDRICAL HEATING FLUID DUCT OF ONE METALAND FIN UNITS OF ANOTHER METAL HAVING A DIFFERENT COEFFICIENT OFEXPANSION AND A SECOND DUCT SURROUNDING SAID UNITS, SAID UNITS HAVINGFIN ELEMENTS PROJECTING RADIALLY FROM SAID DUCT AND BEING ELONGATED INTHE AXIAL DIRECTION OF SAID DUCT, SAID FIN ELEMENTS BEING FORMED INPAIRS EACH OF WHICH COMPRISES A SHEET OF SAID OTHER METAL BENTINTERMEDIATE ITS WIDTH TO FORM A CENTRAL LONGITUDINAL LOOP AND WITH ONEOF SAID FIN ELEMENTS AT EACH SIDE OF SAID LOOP TERMINATING IN A FREEEDGE, SAID FIN UNITS BEING SOLDERED TO SAID DUCT BY MEANS OF CONTINUOUSSOLDERING THROUGHOUT THE LENGTHS OF SAID LOOPS, EACH OF SAID FINELEMENTS HAVING A TRANSVERSE SLOT IN ITS RADIALLY OUTER PORTION, SAIDSLOTS HAVING THEIR RADIALLY INNER EXTREMITIES TERMINATING IN RELATIVELYCLOSE PROXIMITY TO SAID LOOPS, AND A BINDING WIRE AROUND SAID UNITS INSAID SLOTS.